In many parts of the world, isolated land masses exist which require the importation of fossil fuels to generate electrical power. The Hawaiian Islands are an example of such land masses; and power generation is presently limited to conventional fossil-fueled plants using steam or gas turbines which produce undesirable atmospheric pollutants. In an effort to improve the environment, it has been proposed to utilize geothermal sources to produce power. If the geothermal sources are present on certain outlying islands, the power produced can be sent to the main islands, for example, by conventional underwater power transmission lines. Because the normal electrical load in the islands is such that the load during the day or periods of peak power demand greatly exceeds the load at night, or during periods of off-peak power demand, geothermal power plants inherently are not totally suitable. The problem is that a geothermal power plant usually operates at rated capacity all the time, both day and night. Thus, a plant capable of supplying the daytime load would have excess capacity at night. Because of the geographical isolation of the plant, it is not practical to transmit the excess power produced at night to another customer; and for this reason, large scale geothermal power plants are often not appropriate for the conditions described above. Consequently, conventional fossil-fueled power plants are supplemented by fast starting gas turbine power units for daytime peaking because these units can be brought on and off line quickly. Generating electricity using conventional oil-fired plants using steam turbines for base line power production supplemented by gas turbine peaking is both expensive and polluting.
Geothermal power plants are cost effective, but the nature of these plants is not conducive to quickly starting and stopping, which means that the substitution of such plants for conventional fossil-fueled plants is not practical in a geographically isolated location where excess power at night cannot be disposed of. One approach to this problem is to vent the geothermal production wells at night, and reduce the operating level of the plant to accommodate the low level load during the night. This approach is not desirable because geothermal vapors contain noxious gases which, when released to the atmosphere, are dangerous to human health. Treatment systems exist for removing noxious gases, but the cost of this equipment is prohibitive. It is therefore an object of the present invention to utilize a geothermal power plant in a new and different way so as to avoid the problems with the prior art as outlined above.